Gastric Acid Reducing Agents

Beta-caroteneBeta-carotene: According to human study, proton pump inhibitors, such as esomeprazole (Nexium®), lansoprazole (Prevacid®), omeprazole (Prilosec®, Losec®), rabeprazole (Aciphex®), and pantoprazole (Protonix®, Pantoloc®), may cause a loss of stomach acid and may reduce absorption of a single dose of beta-carotene (8839509).

BoronBoron: Based on human evidence, magnesium may interfere with the normal physiological effects of boron in the body (3678698). Sources of magnesium may include antacids containing magnesium oxide or magnesium sulfate (milk of magnesia, Maalox®).

CalciumCalcium: Based on human evidence, use of proton pump inhibitors (lansoprazole, omeprazole, rabeprazole sodium) and calcium carbonate or calcium phosphate at the same time may cause decreased absorption of calcium salts (18254877). A human study that evaluated omeprazole (a proton pump inhibitor) and its effect on calcium suggests that the gastric acid inhibition associated with omeprazole may reduce calcium in patients with phosphate-induced hyperparathyroidism (8538929). Human studies have not shown an interaction between H2 blockers (i.e famotidine) and calcium levels (17722708). Based on human studies, aluminum-containing antacids may decrease the absorption of calcium (7091034, 4067833).

CopperCopper: Based on secondary sources, antacids may interfere with copper absorption. Human evidence involving hemodialysis patients, however, provides conflicting evidence, suggesting that copper status may be unaffected by the use of antacids (10999426). Based on animal study, H2 blockers such as cimetidine may bind free copper ions (radicals) (12542899).

Folic acidFolic acid: Based on secondary sources, chronic use of large doses of antacids may reduce folic acid absorption, but this reduction is likely only noteworthy if dietary folate intake is very low. Secondary sources indicate that maintenance of the recommended daily intake of folic acid in the diet may be recommended. Based on human study, use of antacids (containing aluminum and magnesium hydroxide) may reduce folic acid absorption (2902178). Based on human study, sulfasalazine may interact with reduced folate carrier and may lead to a folate deficiency for which supplementation may be necessary (15248210). Based on human data, folic acid absorption from the small intestine is optimal at pH 5.5 to 6, and in theory, the increased pH associated with the use of H2 blockers (such as cimetidine (Tagamet®), famotidine (Pepcid®), nizatidine (Axid®), and ranitidine (Zantac®)) may therefore reduce folic acid absorption (2902178).

IronIron: Based on a review, antacids (specifically H2-receptor antagonists) may reduce iron absorption, and reduced efficacy has occurred occasionally (2905759). This effect, however, may be more clinically relevant with long-term use of H2-receptor antagonists. Based on human study, antacids containing aluminum salts may not reduce iron levels (17691589). Based on a review and human study, proton pump inhibitors may also reduce non-heme iron absorption (19262546, 17344278).

PhosphorusPhosphorus: Based on human evidence, people taking sucralfate may develop lower than normal blood levels of phosphorus (3514490). Antacids containing aluminum, calcium, or magnesium may bind phosphate in the gut and prevent its absorption, potentially leading to hypophosphatemia (low phosphate levels) when used chronically. Based on human evidence, aluminum salts may reduce serum phosphate levels (16211530). Based on human evidence, proton pump inhibitors and H2 blockers may cause an increase in calcium in hemodialysis patients (17722708).

SeleniumSelenium: Based on secondary sources, agents that alter the pH of the stomach may decrease selenium absorption.

ThiaminThiamin: Based on human case reports, antacids may lower thiamin levels in the body by decreasing absorption and increasing excretion or metabolism (7412923).

Vitamin B12Vitamin B12: Based on human evidence, a fall in vitamin B12 status may result from decreased stomach acid caused by acid blocking drugs, including lansoprazole (7706591). The reduced secretion of gastric acid and pepsin produced by proton pump inhibitors (PPIs) may reduce absorption of protein-bound (dietary) vitamin B12, but not supplemental vitamin B12. Reduced vitamin B12 levels may be more common with PPIs than with H2-blockers, because they are more likely to produce achlorhydria (complete absence of gastric acid secretion). However, vitamin B12 deficiency may be unlikely, unless PPI therapy is prolonged (two years or more) or dietary vitamin intake is low. Based on human evidence, researchers conclude that vitamin B12 levels should be monitored in people taking high doses of PPIs for prolonged periods (19262546, 18924330, 18294598). Based on human evidence, patients with Zollinger-Ellison syndrome using omeprazole therapy chronically may develop vitamin B12 deficiency (9626024). Folate levels, however, may have not been reduced. Based on human evidence, H2 blockers may cause a vitamin B12 deficiency, and may be relevant for those who are receiving H2-receptor antagonist treatment for more than two years (1358279) .

Vitamin CVitamin C: Based on human evidence, the use of proton pump inhibitors, such as omeprazole, may reduce plasma vitamin C levels (16167970).

Vitamin DVitamin D: Based on in vitro evidence, cimetidine may reduce vitamin D activation by the liver (4022464).

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.